Clamp



FIG. 1 is a top view of a clamp showing my new design;

FIG. 2 is a left side view thereof, the right side being a mirror image;

FIG. 3 is a bottom view thereof;

FIG. 4 is a front view thereof;

FIG. 5 is a rear view thereof. 

The ornamental design for a clamp, as shown and described. 